Tetrachloroethylene (also called perchloroethylene or PCE) is a commonly used industrial solvent and is a frequent drinking water contaminant. While studies of adult PCE exposure have demonstrated numerous neurotoxic effects, little is known about the long-term nervous system effects of gestational and childhood exposures. The proposed epidemiologic study will test the hypothesis that prenatal and childhood exposure to PCE-contaminated drinking water is associated with the following neurotoxic effects: increased prevalence of indicators and diagnoses related to developmental disorders of learning and attention, and vision disorders; impaired performance on neuropsychological and vision tests; and increased prevalence of cerebral pathology and dysfunction as seen in structural and functional neuroimaging studies. The proposed population-based retrospective cohort study, an extension of our ongoing SBRP project, will include approximately 3,000 individuals with developmental exposure to PCE-contaminated drinking water and a comparable group of 3,000 unexposed individuals. The exposed group will include individuals with prenatal and childhood PCE exposure combined, and their older siblings with only childhood exposure. Exposure to contaminated drinking water occurred from 1969 through 1983 when PCE leached from the vinyl lining of asbestos-cement water distribution pipes. Cohort members, who are now adults, will be identified, traced, and sent self-administered questionnaires to obtain information on the outcomes and confounding variables. Neuropsychological and vision tests, and neuroimaging studies will be conducted in subsets of highly exposed and unexposed subjects. Exposure to PCE-contaminated drinking water will be estimated using improved exposure assessment methods. Each outcome will be examined in relation to the time of developmental PCE exposure while controlling for confounding variables. The interaction between PCE exposure and alcohol consumption will also be examined.